Simulation Analysis Of Asphalt Mixture Compaction Based On Digital Image Processing Technology

The early damage of asphalt pavement is closely related to its compactness in the compaction process.Although the traditional indoor test can effectively measure the characteristics of the asphalt pavement,this method still has great limitations.It cannot understand the microstructure changes of the asphalt pavement under the premise of complete asphalt pavement.Aiming at the shortcomings of traditional tests,this paper uses particle flow discrete element software PFC and digital image processing technology to build a two-dimensional asphalt pavement model,and then performs simulation compaction and biaxial compression numerical experiments on the model,and obtains some relevant conclusions.Subsequent research provides a certain reference.First,obtain random images of asphalt aggregates through the image acquisition device,and perform gray-scale binarization and other processing on the collected images.Use several sets of detection operators to find the contours of the image,and after analyzing the results,use the Canny operator to find the boundaries of other images.Secondly,optimize the contour boundary with the idea of “Replace Curves with Straight Lines”,use the pixels on the image to indirectly obtain the composition parameters of the coarse aggregate contour(such as centroid,area,etc.).The main shape parameters explored are the ratio of long and short axis,angularity index,and area difference,among which the measured composition parameters are used to calculate the shape parameters of irregular particles.Subsequently,the irregular particle contour filling algorithm is used to fill the contour boundary to obtain the unit particle model;choose a suitable contact model,randomly select a unit particle model according to the gradation characteristics of the asphalt mixture,and establish a 100mm×200mm asphalt compaction mode;a flat cluster-shaped block simulation roller was established in the PFC2 D software;the cluster-shaped block was applied to the asphalt compaction model,and the operating parameters of the vibratory roller were assigned to the cluster-shaped block.Finally,the impact of compaction operation parameters(such as rolling load,coarse aggregate content,coarse aggregate shape parameters and coarse aggregate principal axis angle,etc.)on the compaction characteristics of asphalt mixtures is explored.Perform a biaxial compression numerical test on the obtained model and check the test results.The results show that coarse aggregate content,aggregate shape and coarse aggregate principal axis angle have a great influence on compaction performance;the compaction effect of the sample under the change of 30%～35% and 50%～70% of the coarse aggregate content is better.The shear strength of the pavement becomes higher as the proportion of coarse aggregate(in the range of 30% to 70%)becomes smaller;when axis are equal to 1.5,the compaction of the asphalt pavement is relatively good,and the shear strength of the mixture becomes smaller as the ratio of length to minor axis becomes higher;when the number of inclination angles of the coarse aggregate is 90°,the compaction density of the asphalt mixture is relatively best.